RESUMEN
Breeding strategies based on molecular markers have been adopted by ex-situ conservation programs to assess alternative parameters for the genetic diversity estimates. In this work we evaluated molecular and studbook data for captive populations of black-lion-tamarin (BLT), an endangered primate endemic to Brazil's Atlantic Forest. Pedigree analyses were performed using BLT studbook information collected from 1973 to 2018. We analyzed the whole captive population since its foundation; the current captive population (CCP); and all extant BLTs in the Brazilian captive population (BCP), separately. Microsatellite analyses were implemented on the BCP individuals from the eighth generation (BCP-F8) only to avoid generation overlap. The expected heterozygosity for BCP-F8, using molecular, data was 0.45, and the initial expected heterozygosity was 0.69. Kinship parameters showed high genetic relationships in both pedigree and molecular analyses. The genealogy-based endogamy evidenced a high inbreeding coefficient, while the molecular analyses suggested a non-inbreeding signature. The Mate Suitability Index showed detrimental values for the majority of potential pairs in the CCP. Nevertheless, some individuals evidenced high individual heterozygosity and allele representation, demonstrating good potential to be used as breeders. Thus, we propose the use of molecular data as a complementary parameter to evaluate mating-pairs and to aid management decision-making.
Asunto(s)
Especies en Peligro de Extinción , Variación Genética , Genética de Población/métodos , Leontopithecus/genética , Animales , Animales de Zoológico , Brasil , Cruzamiento , Conservación de los Recursos Naturales/métodos , Conservación de los Recursos Naturales/estadística & datos numéricos , Femenino , Bosques , Genética de Población/estadística & datos numéricos , Genotipo , Heterocigoto , Masculino , Linaje , Dinámica PoblacionalRESUMEN
Leontopithecus caissara is a critically endangered primate species from the Brazilian Atlantic Forest. Nineteen microsatellite loci, previously developed for congeneric species, were tested with 34 L. caissara individuals from Superagüi Island. Of the 19 loci, 17 (89.4 percent) produced robust alleles, nine (47.4 percent) of these proved to be polymorphic, with a total of 23 alleles and an average of 2.56 alleles per locus. Expected and observed heterozygosity averaged 0.483 and 0.561, respectively. The exclusion power for identifying the first parent of an arbitrary offspring was 0.315 over all loci. The results thus indicate both the usefulness and limitations of these nine microsatellite loci in the genetic analysis of L. caissara, as well as their potentiality for genetic investigation in other congeneric species.
RESUMEN
A preliminary qualitative analysis of genetic variability status in Astyanax fasciatus (Cuvier, 1819) from upper Tibagi River headwaters and Vila Velha State Park (VVSP) was carried out by enzymatic digestion (RFLP) of D-Loop region from mtDNA. The results showed that Tibagi and VVSP populations were genetically different.
Uma análise qualitativa da variabilidade genética em Astyanax fasciatus (Cuvier, 1819) do alto Rio Tibagi e Parque Estadual de Vila Velha (PEVV) foi conduzida por digestão enzimática (RFLP) da região D-Loop do mtDNA. Os resultados evidenciaram que essas populações são geneticamente diferentes.
RESUMEN
Among the anostomid fishes, the genus Leporellus is represented by only three species: L. nattereri, endemic of the Amazon River, L. retropinnis, endemic of the Piracicaba River, and L. vittatus, widely distributed in rivers from Peru, Colombia, Guianas, and different major hydrographic basins of Brazil. A cytogenetic study carried out on specimens of Leporellus vittatus from three major Brazilian hydrographic basins evidenced a karyotype of 54 metacentric and submetacentric chromosomes. C-banding analysis revealed the presence of large pericentromeric heterochromatic segments in all chromosomes and a telomeric block coincident with the NOR sites. Ag, CMA3 or MM staining, and FISH with ribosomal probes located the 45S ribosomal genes on the terminal region of the long arm of the 12th chromosome pair of all populations. Nevertheless, in the specimens from the Paraná and São Francisco Basins the 5S rDNA clusters were interstitially located by FISH on the long arm of the 2nd chromosome pair, while in the specimens from the Tocantins-Araguaia Basin these sites were observed on the long arm of the 9th chromosome pair and on the short arm of the 17th chromosome pair. These data suggest that the species currently named Leporellus vittatus may comprise a complex of cryptic species.
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Animales , Mapeo Cromosómico , Peces/genética , Brasil , Bandeo Cromosómico , Cariotipificación , Peces/clasificaciónRESUMEN
Cytogenetic analyses performed in populations of the Neotropical freshwater fish Leporinus elongatus of the Upper Paraná River basin showed a chromosome polymorphism involving heterochromatic segments of the nucleolar organizing pair in this species. The NOR-bearing chromosome pair was characterized by two phenotypes identified by the absence (CÕ) or presence (C²) of a heterochromatic segment located in an interstitial position of the long arm in this pair. The meiotic segregation of these variations results in three distinct cytotypes, CÕCÕ, CÕC² and C²C². Both populations were in Hardy-Weinberg equilibrium. Sex-related cytotype divergence was identified and multivariate analyses revealed that the C²C² individuals presented morphometric differentiation relative to body height in relation to the other cytotypes. A chromosome differentiation and a cytotype proportion difference observed between both populations suggest the occurrence of population subdivision within this species along the Upper Paraná River basin. These findings might contribute to the knowledge of the population biology of this fish and for its conservation.
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Animales , Análisis Citogenético , Genética de Población , Peces/genética , Variación Genética , Región Organizadora del Nucléolo , Polimorfismo GenéticoRESUMEN
Although several cases of natural triploidy in fish have already been described, spontaneous polyploidy in species with differentiated sex chromosomes are rare. We report the occurrence of a triploid fish (3n = 81) Leporinus cf. elongatus, a species characterized by a highly differentiated ZZ/ZW sex chromosome system, from the São Francisco river. The occurrence of a ZZZ triploid adult indicates the viability of this chromosome constitution in this fish.
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The culture of the marine shrimp Litopenaeus vannamei has recently boosted the Brazilian shrimp industry. However, it is well known that selection methods based solely on phenotypic characteristics, a reduced number of breeders and the practice of inbreeding may promote a significant raise in the genetic similarity of the captive populations, leading to greater disease susceptibility and impairing both the growth and final size of the shrimps. We used four microsatellite loci to investigate genetic variation in three generations (F5, F6 and F7) of a closed and reared L. vannamei lineage. Although an accentuated heterozygosis deficit was detected, we also observed that the captive propagation of this lineage did not lead to a significant loss of genetic variability over the three generations studied. One possible reason for this is that the breeding conditions of this lineage were good enough to prevent any significant loss of genetic variability. However, three generations may have been insufficient to produce detectable changes in genetic frequencies in the loci studied. Alternatively, the microsatellite loci may have been non-neutral (biased) and related to the conditions in which the shrimps were kept, resulting in a similar allele pool in respect to these four microsatellites over the three generations studied. Any generalizations regarding microsatellite variation in closed shrimp lines may thus be incomplete and should be carefully analyzed.
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We performed an in silico analysis of all microsatellites so far described for penaeid shrimp and for which the polymorphic behavior has previously been analyzed. The objective of the study was to evaluate the structural characteristics of these microsatellites and identifying patterns which allow the characterization of the nature of these sequences in the penaeid genome. All data were compiled in a free-access database specially constructed for this study. Three hundred non-mononucleotide polymorphic microsatellite loci described for 12 shrimp species belonging to the family Penaeidae were analyzed and simple and compound microsatellites with di-, tri-, tetra-, penta- and hexanucleotide motifs were found. Dinucleotides and trinucleotides were the most frequent motifs among both the simple and the compound microsatellites. Although a certain bias related to different microsatellite isolation methodology could not be discarded, it is possible that part of this microsatellite abundance reflects some degree of conservation of microsatellite motifs among the different species. There was a pronounced motif variability within and between species, indicating high differentiation dynamism of these repetitions in this animal group. This study not only sheds light on the structure of the microsatellites present in the penaeid shrimp genome but also resulted in the free-access Penaeid Shrimp Microsatellite Database (available at http://www.shrimp.ufscar.br) which may be very useful for optimizing the use of these microsatellites.
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In the constantly growing Brazilian shrimp industry the evaluation of genetic relationships between broodstocks is an useful tool for shrimp culture management programs. We established the genetic relationships between five broodstocks of the white marine shrimp Litopenaeus vannamei (Penaeidae) based on the sequencing of the mtDNA 16S rRNA and cytochrome oxidase I (COI) regions. Although no divergence was found between the broodstocks for the highly conservative 16S rRNA gene, we did find an 8.2 percent distance between L. vannamei and the Farfantepenaeus subtilis. Analyses of the COI region showed genetic distances of only 0.2 to 1 percent between the broodstocks, which contrasted with the 10.9 percent mean distance found between L. vannamei and F. subtilis. The small genetic distance values obtained may be related to genetic drift or a founder effect that occurred during broodstocks establishment. The mtDNA analysis was able to characterize the genetic divergence between the broodstocks studied and could be helpful for defining better management strategies of these crustacea.
Asunto(s)
Animales , ADN Mitocondrial , Variación Genética , Penaeidae/genética , Reacción en Cadena de la Polimerasa , ARN Ribosómico 16SRESUMEN
The Pacific white shrimp, Litopenaeus vannamei (Penaeidae), represents about 95 percent of all Brazilian shrimp production. The Brazilian L. vannamei foundation broodstock was made up of specimens collected from different American Pacific sites, but little information was collected on the genetic structure of the broodstock. We used the fluorescence amplified fragment length polymorphism (fAFLP) method to study the genetic diversity of L. vannamei broodstock lines 03CMF1 and 03CBF1 originally produced by breeder-shrimps imported mainly from Panama and Ecuador, although wild individuals from other localities may also have been used in producing these two lines. Our results showed a total of 93 polymorphic bands ranging from 50 to 500 bp, the mean Nei's genetic diversity calculated for the total sample was 13.4 percent and identity and genetic distance analyses indicated high genetic homogeneity within and between both the broodstock lineages studied which suggests that they had similar genetic structure. These results may represent an important tool for the appropriate management of L. vannamei broodstocks.
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Animales , Penaeidae/genética , Polimorfismo Genético , Variación GenéticaRESUMEN
Damselfishes (Pomacentridae, Perciformes) occur in all major oceans of the world and, with approximately 320 species, represent one of the most diverse families of marine Teleostei. The taxonomy of these reef fishes is problematic because of the large number of complex species and the range of color patterns they display, which vary among individuals and populations of the same species. In this study, we examined the cytogenetic composition of four species of Stegastes (S. pictus, S. fuscus, S. variabilis and S. leucostictus) found along the coast of Brazil. Stegastes pictus had a chromosomal number of 2n = 48 (14m+28sm+2st+4a, fundamental number (FN) = 92), S. fuscus had 2n = 48 (20m+22sm+6a, FN = 90), S. variabilis had 2n = 48 (18m+22sm+8a, FN = 88), and S. leucostictus had 2n = 48, (18m+22sm+8a, FN = 88). The nucleolar organizing regions were single and homologous in all of the species, and were located in the interstitial region on the short arm of the first submetacentric pair. The heterochromatin segments were reduced in size and were distributed conservatively over the centromeric and pericentromeric regions of most of the chromosomes. The marked divergence in the number of chromosomal arms, compared to other perciformes (2n = 48, FN = 48), indicated that varying degrees of multiple pericentric inversions had occurred during the karyotypic evolution of the Pomacentridae. Subtle karyotypic differences between S. variabilis and S. leucostictus suggested a recent divergence or that their karyotypes were less susceptible to changes. These results indicate that cytogenetic analyses could provide important complementary data for the characterization of populations and species of Stegastes and damselfishes in general.
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Animales , Cromosomas , Peces , Inversión Cromosómica , Análisis Citogenético , Hibridación Fluorescente in Situ , CariotipificaciónRESUMEN
A wide range of sex chromosome mechanisms, including simple and multiple chromosome systems is characteristic of fishes. The Leporinus genus represent a good model to study sex chromosome mechanisms, because an unambiguous ZZ/ZW sex chromosome system was previously described for seven species, while the remaining studied species of the genus do not show differentiated sex chromosomes. The occurrence of sex chromosomes in Leporinus trifasciatus and Leporinus sp2 from the Araguaia river, Amazon basin, Brazil, was here investigated. ZZ/ZW sex chromosomes were detected for both species. The Z and W chromosome morphology of L. trifasciatus is the same as described for other species of the genus Leporinus. However, the Z and W chromosomes of L. sp2 were quite different in their morphology and banding pattern suggesting that the ZW system of this species have originated independently from the ZW system previously described for other Leporinus.
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Peces/genética , Cromosomas Sexuales , Animales , Bandeo Cromosómico , Femenino , Peces/clasificación , Cariotipificación , Masculino , Región Organizadora del Nucléolo , Diferenciación SexualRESUMEN
Many factors have contributed to the destruction of fishhabitats. Hydroelectric dams, water pollution and otherenvironmental changes have resulted in the eradication ofnatural stocks. The aim of this study was to detect the genetic variation in Prochilodus marggravii from three collection sites in the area of influence of the Tres Marias dam (MG) on the Sao Francisco river (Brazil), using the RAPD technique. The results obtained revealed that the fish in the downstream region nearest the dam have a higher similarity coefficient than those from the other sampling sites that may be related to differences in environmental characteristics in these regions.Additionaly, significant differences in the band frequencies were observed from one collection site to another. These both findings suggest the occurrence of a structured population and have important implications for the conservation of the genetic variability of distinct natural P. marggravii stocks
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Animales , Peces , Variación Genética , Técnica del ADN Polimorfo Amplificado AleatorioRESUMEN
Neotropical parrots are among the most threatened groups of birds in the world, and many species are facing extinction in a near future. At the same time, the taxonomic position of many species remains unclear. Karyotype analysis has been used to elucidate the phylogenetic status of many bird groups, also providing important information for both in situ and ex situ conservation plans. The objective of the present study was to describe for the first time the karyotypes of the endangered Hyacinth Macaw, Anodorhynchus hyacinthinus, and of the Hawk-headed Parrot, Deroptyus accipitrinus. A diploid number of 2n = 70 and a karyotype similar to the main pattern previously found for the genera Ara, Cyanopsitta, Aratinga, Propyrrhura, Pionites, Pionopsitta, Nandayus, and Guaruba were found for both species. These karyotype descriptions can be a starting point for the genetic monitoring of these two declining species
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Animales , Masculino , Femenino , Aves , Cromosomas , Conservación de los Recursos Naturales , Variación Genética , Citogenética , Genética de Población , CariotipificaciónRESUMEN
The genetic variation in two farmed strains (F3-Panama and F17-Venezuela) of the shrimp Litopenaeus vannamei was examined based on DNA multiloci analyses. Eighteen adults of each strain were analyzed by PCR using a set of VNTR core sequence primers. Genetic similarity, mean allele frequency, mean heterozygosity and the frequency of polymorphic loci were determined for both strains. A dendrogram of genetic similarity was produced by UPGMA clustering. The results for three primers (INS, M13, YN73) revealed different levels of genetic variation within the strains. The higher genetic similarity seen within strain F17 was apparently related to inbreeding, although a bottleneck effect could not be discarded. The low level of genetic variability of this strain could account for the reduced adaptive advantage of these animals and their inability to adjust to breeding conditions in Brazil
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Animales , Decápodos/genética , Variación Genética , Repeticiones de Minisatélite , Reacción en Cadena de la PolimerasaRESUMEN
Säo descritos os cromossomos supranumerários observados em cinco espécies de peixes pertencentes a quatro famílias distintas de caraciformes neotropicais. Esses cromossomos mostraram-se pequenos, totalmente heterocromáticos e acrocêntricos em Leporinus friderici e Leporinus sp. e metacêntricos e totalmente heterocromáticos em Cyphocharax modesta e Prochilodus nigricans. Em Characidium cf. zebra um pequeno extra acrocêntrico é visto totalmente eucromático. Um pequeno segmento rico em pares de bases GC pôde ser observado no cromossomo extra de Leporinus sp. após a coloraçäo com cromomicina A3. Alguns aspectos relacionados à origem desses cromossomos extras entre os caraciformes säo discutidos.
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Animales , Aberraciones Cromosómicas , Peces , Peces/anomalías , CariotipificaciónRESUMEN
Foram analisados os cromossomos de duas espécies de peixes do gênero Brycon (B. lundii e B. microlepis) e de Salminus hilarii. Principalmente baseado no padräo de distribuiçäo da heterocromatina constitutiva, foram discutidas as relaçöes cariotípicas dentro e entre os grupos Bryconinae e Salminae. É sugerida uma origem monofilética para o gênero Brycon, com pelo menos duas sinapomorfias cromossômicas (presença de dois grandes submetacêntricos apresentando blocos pericentromérico e telomérico de heterocromatina constitutiva). Ainda, Bryconinae e Salmininae, compartilhando vários caracteres cromossômicos, podem formar uma unidade monofilética entre os Characidae, na qual outros caracídeos näo estäo incluídos.
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Animales , Citogenética , Peces/genética , Heterocromatina , Cromosomas , Colorantes Fluorescentes , CariotipificaciónRESUMEN
O presente trabalho descreve o cariótipo e a localizaçäo das regiöes organizadoras de nucléolos de 10 espécies de peixes Sul-americanos da família Curimatidae. Os resultados mostram que, a despeito de ocorrerem modificaçöes na estrutura interna dos cormossomos, evidenciadas pelo deslocamento das NORs, a macroestrutura cariotípica deste animais é bastante estável caracterizando um tipo de evoluçäo cromossômica que mantém os cariótipos quase-idênticos, porém, näo totalmente conservados. A identificaçäo dos NORs nas diferentes espécies possibilitou a apresentaçäo de algumas consideraçöes citotaxonômicas